The invention discloses a matching device and matching method for an ultrasonic power supply. The matching device for the ultrasonic power supply comprises an ultrasonic signal generator, a drive isolation circuit, an ultrasonic power amplification circuit, a matching transformer, a tuning inductor, an ultrasonic transducer, a voltage sampling circuit, a current sampling circuit, a filtering and shaping circuit, a phase discriminator, an A / D converter, a single-chip microcomputer and a stepping motor. The output end of the matching transformer is connected with the tuning inductor; the output end of the tuning inductor is connected with the ultrasonic transducer; the voltage sampling circuit is used for collecting real-time working voltage signals at the two ends of a unit formed by the tuning inductor and the ultrasonic transducer, and transmitting the real-time working voltage signals to the phase discriminator. According to the matching device and matching method for the ultrasonic power supply, static impedance matching and dynamic impedance matching can be achieved, the matching inductance value can be tracked and adjusted through the phase difference of working currents and working voltages of the ultrasonic transducer, it can be ensured that the ultrasonic transducer always works at a resonance point, the maximum useful power output of the ultrasonic transducer can be achieved, in addition, the adjusting response speed is high, and accuracy is high.